Composite material bone implant

ABSTRACT

Radiolucent composite implants. Some embodiments include reconfiguration indicators. Some embodiments include radio-opaque markers, especially along contours. Some embodiments are provided in kit form with accessories such as radiolucent drill guides and/or drives. Some embodiments have fiber reinforcement adapted for various usage scenarios. Some embodiments include metal components, for example, to increase strength. Also described are manufacturing methods.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.13/702,334 filed on Dec. 6, 2012 which is a National Phase of PCT PatentApplication No. PCT/IB2011/052468 having International Filing Date ofJun. 7, 2011, which claims the benefit of priority under 35 USC §119(e)of U.S. Provisional Patent Application Nos. 61/344,182 of Beyar filed onJun. 7, 2010, 61/443,308 of Beyar, et al. filed on Feb. 16, 2011 and61/486,280 of Beyar et al. filed on May 15, 2011.

PCT Patent Application No. PCT/IB2011/052468 is also related to PCTPatent Application No. PCT/IB2010/050225 to Beyar, filed on Jan. 18,2010.

The contents of the above applications are all incorporated by referenceas if fully set forth herein in their entirety.

FIELD OF INVENTION

The present invention in some embodiments thereof, relates to compositematerial bone implant components, devices and systems, and/or to methodsfor manufacturing and using such components, devices, and systems, andto surgical instrumentation and procedures used during implantation.More particularly, but not exclusively, the invention relates tobone-supporting components such as bone nails and bone plates, toimplant fixation components such as bone screws and pegs, formed offiber-reinforced polymer matrix composites or self-reinforcing polymers,and to tools and accessories for performing surgery using suchcomponents.

As used herein, the term “bone implants” encompasses, but is not limitedto, hip joints, knee joints, shoulder joints, bone screws, boneinstruments, bone plates, pegs, and intramedullary nails, includingproximal femur nails, typically including screw holes for receiving bonefixation screws, as well as dental bone implants.

BACKGROUND OF THE INVENTION

Bone-supporting components such as bone plates and intramedullary nails(bone nails) have become a treatment of choice for the fixation of bonefractures, especially fractures of long bones (e.g., the humerus, tibiaand femur), and in non-broken bones to prevent fractures. Typically,bone nails are rod-shaped devices configured and constructed to besecured (interlocked) to a bone using one or more fixation componentswhich anchor the bone nail into the bone in order to carry the loadsuntil the bone fracture is cured.

Bone plates are generally (but not exclusively) used in cases that abone nail can't be used, and are designed for implantation on the bonesurface.

Implant fixation components include bone screws, rods and pegs. Bonescrews are used for fixation at one or both ends of a nail or along abone plate Implant fixation components generally referred to as “pegs”are round unthreaded rods (or threaded at one end), conventionallyformed of metal that are usually (but not exclusively) used to helpanchor bone plates to a bone such as the proximal humerus or the distalradius for fracture fixation. The rod goes into a hole drilled into thebone.

In the art, the entire implant is generally constructed from metal, suchas titanium, stainless steel, or a cobalt-chromium alloy. Althoughmetallic implants provide numerous advantages, they also have a fewdrawbacks. Metal construction normally provides adequate bendingstrength, thus reducing problems associated with implant fracture.However, the rigid metal implant creates a relative high degree ofstresses in certain regions of the bone, while, on the other hand, doesnot provide for sufficient load transfer resulting in stress shielding.Both high stress and stress shielding can cause bone deterioration andresorption, leading to areas of bone weakness and loss of bone supportfor the implant (e.g., intramedullary nails and stem components of jointreplacement systems). In addition, metals may result in artifacts in CTand MR imaging. In addition metals can mask (i.e., block) radiationtreatment in cancer cases. Furthermore, metals such as stainless steeland cobalt chromium may cause biocompatibility problems related tocorrosion and sensitization reaction (mainly due to allergy to nickel).

Also, conventional metal fixation components, e.g., bone-supportingcomponents (e.g., intramedullary nails and bone plates) and pegs andscrews can mask the fracture and limit the ability of the surgeon to setthe fracture correctly. Metal bone-supporting components and fixationcomponents may also limit the ability to see the healing process inX-Rays.

Non-metal implants made of a lighter and more flexible material, yethaving sufficient strength for load bearing, have been suggested in thepast. In particular, composite material implants, for example formed ofpolymer reinforced with fibers, are disclosed in U.S. Pat. Nos.4,750,905, 5,181,930, 5,397,358, 5,009,664, 5,064,439, 4,978,360,7,419,714 the disclosures of which are incorporated herein by reference.

U.S. Pat. No. 5,009,664 describes a tubular, curved marrow nail, made ofcarbon fibers, which are preferably knit in a crisscross fashion,saturated in a hardenable plastic, with a conically tapered distal tip.

U.S. Pat. No. 5,181,930 describes an implant comprising an elongatedcore formed of continuous filament fibers embedded in thermoplasticpolymer. The core is encased within a filler, made of a non-reinforcedpolymer which is molded around the core to proximate the final desiredshape of the implant. A sheath, composed of reinforced fibers embeddedin a polymer, is spiral wound around the filler, at angles(orientations) which may vary along the implant axis.

Although known composite material implant technology can provide severaladvantages, there are also some limitations. In contrast to metal,composite material implants are radiolucent, i.e., do not block most ofthe radiation coming from x-ray systems such as fluoroscopy, and hencetheir implantation and tracking during follow-up may be difficult. Forbone nails or plates, accurate insertion of the screws into the holes inthe nail/plate is crucial to the success of the operation, especiallywhere no aiming device is used.

U.S. Pat. No. 7,419,714 describes a bone screw or plate formed of acomposite of polymer or ceramic material.

Currently available bone implants, such as bone plates, includepre-drilled holes for the fixation devices which anchor the implant tothe bone and optionally lock the implant in place and/or provide forbone fragments compression.

SUMMARY OF THE INVENTION

There is provided in accordance with an exemplary embodiment of theinvention, a bone implant component comprising bone plate formed of afiber-reinforced polymer composite in which the reinforcing fibers arealong the length of the plate,

wherein the bone plate is radiolucent.

In an exemplary embodiment of the invention, the component includes atleast one radiopaque marker that delineates at least part of the contourof plate. Optionally the marker is comprised of a metal wire.

There is provided in accordance with an exemplary embodiment of theinvention, a bone-supporting component formed of a fiber-reinforcedpolymer composite configured to be anchored by a plurality of fixationcomponents received in passages therein,

wherein at least some features of the component not preformed so that itmay be reconfigured by the surgeon during the implantation procedure byforming the required features.

In an exemplary embodiment of the invention, the features are drilledand/or tapped passages, or cut or sawed portions.

Optionally or alternatively, the component is further including at leastone built-in reconfiguration guide to facilitate formation of fixationcomponent passages or for otherwise reconfiguring the bone-supportingcomponent. Optionally, the reconfiguration guide includes one or moreindentations in the surface of the component. Optionally, theindentations form blind holes, or blind slots, or elongated blindgrooves, or cutting lines.

In an exemplary embodiment of the invention, the component is furtherincluding at least one pre-drilled passage for receiving a fixationcomponent.

There is provided in accordance with an exemplary embodiment of theinvention, a fixation component for a bone implant formed of afiber-reinforced polymer composite having a body and a head at theproximal end of the body which is integrally formed with the body,

wherein the body includes an elongated portion having longitudinalreinforcing fibers disposed along its length, and

the head includes reinforcing fibers disposed mainly in a circular orspiral pattern.

There is provided in accordance with an exemplary embodiment of theinvention, a bone implant component, formed mainly of fiber-reinforcedpolymer composite material comprising:

a core including elongated reinforcing fibers to resist mainly bendingforces; and

a sleeve enclosing the core that includes spirally wound fibers toresist mainly torsional forces. Optionally, the component is a bonescrew.

In an exemplary embodiment of the invention, the body further includeschopped fibers of reinforcing material. Optionally, the chopped fibersare of different lengths and/or are non-uniformly oriented.

In an exemplary embodiment of the invention, the reinforcing fibers ofthe sleeve are oriented in a spirally wound layer oriented at 45 degreesrelative to the core.

In an exemplary embodiment of the invention, the sleeve is formed of twoor more spirally wound layers, with alternating layers oppositely woundat about ±45 degrees relative to the longitudinal axis of the core.

In an exemplary embodiment of the invention, the composite material isin the form of pre-impregnated (prepreg) tapes having the fibers runninglength-wise along the tape. Optionally, the cores are formed by layersof prepreg tape disposed one on top of the other. Optionally oralternatively, the sleeves are formed of prepreg tapes, wound spirallyover the core.

There is provided in accordance with an exemplary embodiment of theinvention, a composite implant having fibers having different mechanicalproperties disposed at different places in the implant. Optionally, atleast 20% of the fibers used in the sleeve have different strength intension and different modulus of elasticity from fibers are used in thecores.

There is provided in accordance with an exemplary embodiment of theinvention, a composite bone implant component including at least oneradio-opaque marker located at a distal end of the body, or extendingmost the length of the body. Optionally, the at least one marker isformed of metal wires embedded inside the components. Optionally oralternatively, the at least one marker is formed of a hollow tube.

There is provided in accordance with an exemplary embodiment of theinvention, a bone implant kit comprising:

-   -   a bone-supporting component formed mainly of a fiber-reinforced        polymer composite;

one or more fixation components for the bone-supporting component; and

a radiolucent drill guide to facilitate drilling for insertion of thefixation components. Optionally, the bone-supporting component includespre-drilled passages for the fixation components so that only the boneneeds to be drilled during the implantation procedure. Optionally, thebone-supporting component is supplied undrilled, and both the bone andpassages for the fixation components are drilled during the implantationprocedure.

In an exemplary embodiment of the invention, the bone-supportingcomponent is a radiolucent bone plate.

In an exemplary embodiment of the invention, the kit including anarrangement for removing drilling debris created by drilling forinsertion of a bone implant comprising a suction element configured forconnection to a source of suction and for disposal of a suction port onthe suction element adjacent to a drill bit during drilling; and

In an exemplary embodiment of the invention, the kit further includes anarrangement providing irrigation fluid to a drilling site comprising anirrigation element configured for connection to a source of irrigationfluid,

wherein the irrigation element includes a fluid outlet port configuredto be positioned adjacent to a drill bit during drilling.

There is provided in accordance with an exemplary embodiment of theinvention, a fixation component for a bone-supporting component of abone implant comprising:

a body including a core, a sleeve surrounding the core, and a headportion,

wherein the body is formed of a fiber-reinforced polymer composite; and

a further portion formed of a hard material to strengthen the implantand/or enhance the hardness of the implant and/or to impart surfaceproperties.

In an exemplary embodiment of the invention, the further portion is alayer covering an elongate section of the body or the entire body.Optionally or alternatively, the further portion is a metal coating or ametal tape. Optionally, the fixation component is threaded at least inits distal region, and the metal coating or tape disposed over thethreads. Optionally, the coating or tape is discontinuous, and does notcover the root portions of the threads.

In an exemplary embodiment of the invention, the coating or tape iscontinuous, and a portion covering the crown portions of adjacentthreads extends into and overlaps in the root portions between thethreads. Optionally, at least some overlapping portions are welded.

In an exemplary embodiment of the invention, the further portion is aninsert at the distal end of the component.

There is provided in accordance with an exemplary embodiment of theinvention, a bone implant formed of a fiber-reinforced polymer matrixcomposite comprising:

a bone-supporting component;

a fixation component configured to be received in passages in thebone-supporting component; and

a locking element for attaching the fixation component to abone-supporting component.

There is provided in accordance with an exemplary embodiment of theinvention, a bone implant formed of a fiber-reinforced polymer matrixcomposite comprising:

a bone-supporting component;

a fixation component configured to be received in a passage in thebone-supporting component; and

a sleeve between the fixation component and the passage. Optionally, thesleeve is configured to reduce friction between the fixation componentand the passage. Optionally or alternatively, the sleeve is threaded.

There is provided in accordance with an exemplary embodiment of theinvention, a method of treating a bone fracture comprising:

positioning a bone-supporting component at a desired position inrelation to a fracture site,

wherein the bone-supporting component is formed of a fiber-reinforcedpolymer composite manufactured without pre-drilled passages forreceiving fixation components; and

reconfiguring the bone-supporting component to provide passages for oneor more fixation components or other desired features by removal ofmaterial from the bone-supporting component before or duringimplantation surgery. In an exemplary embodiment of the invention, bonefragments are manipulated while viewing through the component, forexample, using an x-ray imager. Optionally, the bone-supportingcomponent is reconfigured by one or more of drilling, or tapping, orcutting, or sawing. Optionally or alternatively, the reconfiguring isperformed using a radiolucent drill.

In an exemplary embodiment of the invention, the reconfiguring isperformed before or after the bone-supporting component is positioned atthe fracture site.

There is provided in accordance with an exemplary embodiment of theinvention, a method of manufacturing a fixation component for a boneimplant comprising:

compression molding a core of relatively straight elongated fiberswithin a polymer matrix; and

machining the core to form a thread. Optionally, the method includesforming at least one spirally wound layer over the core. Optionally oralternatively, the pitch of the spirally wound layer matches the threadpitch. Optionally or alternatively, the method includes forming aspirally wound profile layer having a cross section substantiallymatching said thread.

In an exemplary embodiment of the invention, the fixation component isformed of prepreg tapes of fiber-reinforced polymer composite.Optionally or alternatively, the method includes forming an externaltitanium layer on the fixation component.

There is provided in accordance with an exemplary embodiment of theinvention, a bone implant component formed of a fiber-reinforced polymercomposite having a body and a head at the proximal end of the body whichis integrally formed with the body,

wherein the body includes an elongated portion having longitudinalreinforcing fibers disposed along its length, and

the head includes a coupling element for coupling the component to aninsertion tool, and is formed with reinforcing fibers disposedcircumferentially or spirally wound around the coupling element.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. In thisconnection, it is stressed that particular features shown in theseembodiments are by way of example and for purposes of illustrativediscussion. Other embodiments may include other combinations of featuresas will be apparent to those skilled in the art from the drawings andthe accompanying description.

In the drawings:

FIG. 1 illustrates a composite material intramedullary nail connected toan insertion handle, in accordance with some embodiments of the presentinvention;

FIG. 2 is a cross-sectional view of the proximal region of the nailshown in FIG. 1;

FIG. 3 is an enlarged perspective view of the proximal region of thenail of FIGS. 1 and 2;

FIG. 4 is a side perspective view of a fixation component according tosome embodiments of the present invention;

FIG. 5 is a cross-sectional view showing schematically a distal sectionof a bone nail anchored by a bone screw as illustrated in FIG. 4,according to some embodiments of the invention;

FIG. 6A is a generally side perspective view of a fixation componentwith a portion that is oversized relative to a passage in a bonesupporting component;

FIG. 6B is a perspective view showing schematically the component ofFIG. 6A installed in a bone-supporting component;

FIG. 6C is a cut-away view of FIG. 6B;

FIG. 6D is an enlarged side-sectional view of the fixation component ofFIG. 6C;

FIGS. 7A-7D, FIGS. 8A-8C and FIG. 9 illustrate composite material bonescrews, in accordance with some embodiments of the invention;

FIGS. 10A-10D illustrates composite material bone screws having anexternal coating according to some embodiments of the invention;

FIG. 11, FIGS. 12A-12B and FIGS. 13A-13B illustrate different compositematerial proximal femur nail and leg screw configurations, in accordancewith some embodiments of the invention;

FIG. 14A is a side elevation view of a bone nail that providesreinforcement at the interface with a bone screw;

FIG. 14B shows a side view of FIG. 14A, rotated 90 degrees;

FIG. 15 is a side view, including a portion in schematic partialsection, showing the orientation of reinforcing fibers in the head of afixation component formed of a fiber-reinforced polymer compositeaccording to some embodiments of the invention;

FIG. 16A is a side view, and FIGS. 16B-16C is transverse sectional viewsthat schematically illustrate options for radiopaque marking of a bonescrew;

FIGS. 17A and 17B are top perspective and longitudinal cross-sectionalviews respectively of a bone-supporting implant component including oneor more blind bores or grooves;

FIG. 18 is a side and top perspective view of a bone plate in which theshaft includes round bores and elongated slots, and a targeting guidewhich may be used to help drill holes in the bone plate head and/or theunderlying bone;

FIG. 19 is a top and side perspective view of a bone plate and a drillsleeve for use in drilling holes for fixation components, and a drillsleeve holder to assist in insertion and removal of the drill sleeve;

FIGS. 20A and 20B top and side perspective and vertical sectional viewsrespectively that illustrate another drill sleeve 670 according to someembodiments of the invention;

FIG. 21 is a top and side perspective view illustrating a combined drilltargeting guide and fixation device insertion accessory according tosome embodiments of the invention;

FIGS. 22A and 22B are schematic top views that illustrate ways toprovide for visualization of bone plates under fluoroscopy duringimplantation and/or at follow-up in some embodiments of the invention.

FIGS. 23A and 23B are assembled and partially exploded views of someembodiments of the invention which may be used to share the loadsexerted on the nail-handle connection area during insertion of the nailinto the bone;

FIGS. 24A and 24B are, respectively, assembled and partially explodedviews similar to FIGS. 23A and 23B showing another nail installationdevice 770 according to some embodiments of the invention;

FIGS. 25A and 25B are partial cut-away views illustrating a portion of aradiolucent connector 790, coupled to a drill power unit 792;

FIGS. 26A and 26B are schematic sectional views that illustrateembodiments of the invention in which provision is made for removal ofdrilling debris;

FIG. 27 shows in flow-chart form, an example of how methods according tosome embodiments of the invention may be performed.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION Overview ofFeatures of Some Embodiments of the Invention

The present invention in some embodiments thereof, relates to compositematerial bone implant components, devices and systems, and to methodsfor manufacturing and using such components, devices, and systems, aswell as to surgical instrumentation and procedures used duringimplantation. More particularly, but not exclusively, the inventionrelates to bone-supporting components such as bone nails and boneplates, to implant fixation components such as bone screws and pegsformed of fiber-reinforced polymer matrix composites.

In the following overview, except as otherwise indicated, it is to beunderstood that the implants described are all formed mainly (e.g., atleast 50%, 60%, 70%, 80% or intermediate amounts of the load bearingportions thereof) of a fiber-reinforced polymer composite.

An aspect of some embodiments of the invention pertains to a boneimplant component, e.g., a bone nail, a bone screw, or a peg formed of acore including different fiber directions and/or types in differentparts thereof. In one embodiment, the implant includes elongatedreinforcing fibers to resist mainly bending forces, optionally in a corethereof. Optionally or alternatively, bone nails and screws or otherfixation elements such as pegs may also have a sleeve enclosing the corethat includes spirally wound fibers to resist mainly torsional forces.

In an exemplary embodiment of the invention, an elongate implant has alength to width ratio of at least 1:2, 1:3, 1:4 or more.

In an exemplary embodiment of the invention, the body includes choppedfibers of reinforcing material. Optionally, the chopped fibers are ofdifferent lengths and/or are non-uniformly oriented.

In an exemplary embodiment of the invention, the reinforcing fibers ofthe sleeve are oriented, for example, at about (e.g., within 5, 10, 20or intermediate degrees of) 45 degrees relative to the longitudinal axisof the core. Optionally, the sleeve is formed of two or more spirallywound layers, with alternating layers oppositely wound at, for example,±45 degrees relative to the longitudinal axis of the core.

An aspect of some embodiments of the invention pertains to implantcomponents in which different types of fibers having differentmechanical properties are used in different places in the implant. Forexample in a nail, longitudinal fibers having high elongation at breakand low modulus of elasticity may be used in the core. In the sleeve,low elongation to break and high module of elasticity, may be preferableso the nail will be elastic for bending and rigid for torsion.

Optionally, the polymer forming the matrix in the various embodimentsdescribed above is polyetherketoneketone (PEKK), polyetheretherketone(PEEK), or any other suitable biocompatible polymer.

Optionally, the composite material forming the components in theembodiments described above is in the form of pre-impregnated (prepreg)tapes having the fibers running length-wise along the tape. Optionallythe cores are formed by layers of prepreg tape disposed one on top ofthe other. In some embodiments of the invention, the sleeves are alsoformed of prepreg tapes, wound spirally over the core.

In some embodiments, all or part of the bone implant is coated with amaterial to improve the implant osteo-conductive and/or osteo-inductiveproperties, to enhance implant ability to integrate in the bone and tosupport bone ingrowth. Optionally, the coating is formed of poroustitanium or hydroxyapatite (HA). Optionally, in some embodiments, one ormore antibiotics to avoid infection, and/or bone morphogenetic proteins(BMP) may be added to the coating in the area of the fracture to promotebone regrowth.

Optionally, a polymer layer is a bioresorbable or biodegradablematerial. Optionally, the layer is formed of polydioxanone orpolycarbonate. These may be used as a coating on the inside of thefixation component-receiving passages or on the entire implant to reducewear of the composite material during implantation.

An aspect of some embodiments of the invention pertains to abone-supporting component e.g., a bone nail or bone plate, configured tobe processed during or right before surgery. In one example, thecomponent is sawn. Optionally or alternatively, the component isdrilled, cut, nibbled, tapped and/or notched or otherwise has materialremoved thereof during surgery or right before. Optionally, theprocessing is decided based on a CT, X-Ray, MRI or visual observation ofa treated area. Optionally, the component is modified even afterimplantation, for example, to add a fixation element (e.g., a screw)therethrough.

In an exemplary embodiment of the invention, the component has aplurality of guide locations or pre-designated locations for processing,for example, in the form of thinned areas, missing areas and/or grooves.

In an exemplary embodiment of the invention, the implant is a plate ornail which is meant to be anchored by a plurality of fixation componentsreceived in passages therein, in which at least some passages are notpredrilled, and the bone supporting component is configured so that atleast some least some fixation device passages may be drilled by thesurgeon during the implantation procedure. (For simplicity, these arecollectively referred to as “undrilled”.)

Optionally, undrilled components include at least one built-inreconfiguration guide to facilitate formation by the surgeon of fixationcomponent passages or for otherwise reconfiguring the bone-supportingcomponent. Optionally, the reconfiguration guide is an indentation inthe surface the component defining blind holes, narrow-diameter holes,dimples, blind slots, elongated blind grooves and/or cutting lines.Optionally, one or more markers (e.g., visual and/or radio-opaque) areprovided to indicate such desired processing locations. Optionally,markers are arranged as a grid, optionally rectangular.

In another example, a nail or other elongate implant is cut to length,for example, at one or both ends, to match a particular patient.

In an exemplary embodiment of the invention, the implant is drilledwhile inside the body. Optionally, suction and/or washing fluid areprovided, for example, for removing debris and/or cooling.

In an exemplary embodiment of the invention, the implant includes atleast one attachment location, for example, a hole, for attaching adrill guide or cutting tool guide thereto, during processing.

In an exemplary embodiment of the invention, instructions for processingare provided on or with the implant, for example, in a packaging.Optionally, one or more size markings are provided on the implant toindicate the effect of such processing.

An aspect of some embodiments of the invention pertains to a boneimplant including a bone-supporting component, e.g., a bone nail or anda fixation component, e.g., a bone screw, each having a body and/or ahead portion at the proximal end of the body which is integrally formedwith the body. In such embodiments, the bodies include elongatedportions having longitudinal reinforcing fibers disposed along theirlength, and the heads include reinforcing fibers disposed mainly in adifferent direction, for example, in a circular or spiral pattern.

An aspect of some embodiments of the invention pertains to combinationof a bone implant including a bone-supporting component, one or morefixation components for the bone-supporting component; and a radiolucentdrill guide to facilitate drilling for insertion of the fixationcomponents.

Optionally, the bone-supporting component includes pre-drilled passagesfor the fixation components so that only the bone is drilled during theimplantation procedure. Optionally, the bone-supporting component issupplied undrilled, and both the bone and passages for the fixationcomponents are drilled during the implantation procedure.

In an exemplary embodiment of the invention, use is made of the factthat the composite implant is mainly transparent (e.g., blocks less than5%, 10%, 30%, 50%, 90% or intermediate amounts of x-ray radiation,depending on the implementation) and bone can be viewed through it. Thisallows, for example, reduction of a fracture, drilling in bone and/orprocessing an implant while the implant is in the body and using x-ray(for example) to view the relative locations of bone fragments and theimplant. Optionally, a plurality of implants are aligned, inside thebody to each other and to bone, using such imaging after implantation.Optionally, non-radiolucent screws are used with such implants.

An aspect of some embodiments of the invention pertains to a fixationcomponent for a bone-supporting component of a bone implant formed of abody optionally including a core, a sleeve surrounding the core, and ahead portion, and a further element formed of a hard material tostrengthen the implant and/or enhance the hardness of the implant and/orto impart other desired properties.

In an exemplary embodiment of the invention, the further element is alayer covering the head portion or the entire body. Optionally oralternatively, the fixation component is threaded at least in its distalregion, and the layer is a metal coating or a metal tape wound over thethreads. Optionally, the layer is discontinuous, and does not cover theroot portions of the threads. Alternatively, the layer is continuous,and the portion covering the crown portions of adjacent threads extendsinto and overlaps in the root portions between the threads.

Optionally or alternatively, the layer is provided in a tool-engagingportion, such as an inner hex-shaped socket or screwdriver receptacle.

Optionally or alternatively, the layer is provided at an interfacebetween a fixation component and a second composite or other material.

An aspect of some embodiments of the invention relates to a method ofreducing wear, debris and/or damage in a composite implant or implantsystem. In an exemplary embodiment of the invention, locations prone towear or damage are covered and/or provided with a metal or polymer layeror element which provides reduced friction, reduced wear and/or largeror small (e.g., as desired) wear particles. In an exemplary embodimentof the invention, the layer is part of a fixation element or a differentimplant. Optionally or alternatively, the layer is a separate component.

In an exemplary embodiment of the invention, fiber direction at alocation of expected wear is oriented perpendicular to a wear direction,so as to reduce damage to an implant.

An aspect of some embodiments of the invention pertains to formation ofa threaded bone screw by compression molding a rod, optionally fromlayered prepreg tapes, followed by machining to form the threads.Alternatively, over the molded core, there is formed a spiral winding,optionally formed of one or more prepreg tape layers, and optionally inwhich winding pitch matches the desired screw pitch. Optionally, whentwo or more layers are used they are wound in alternating clockwise andcounterclockwise orientations.

Optionally, the screw is further machined to produce the desiredconfiguration of the thread teeth. Optionally, a profile winding, forexample that has a relatively triangular cross section is spirally woundaround the core.

An aspect of some embodiments of the invention pertains to fixationcomponents including a locking element for attaching the fixationcomponent to a bone-supporting component. Optionally, the lockingelement is a spring constructed and configured to expand radially toengage within the passage. Optionally, the spring is a locking ring.Optionally the spring is an integral part of a metal portion of thefixation component. Optionally, the locking element is formed by aportion that is oversized relative to the passage. Such a lockingelement is compressed during installation, and re-expands after it exitsthe distal side of the passage. Optionally the fixation component isslightly larger than the passage in the supporting implant, and duringinsertion, is compressed locally the supporting implant and lock intoit.

An aspect of some embodiments of the invention pertains to bone implantcomponents that include radiopaque markers. Optionally, in the case ofthe fixation component or a bone nail, the marker is located at a distalend of the body, or extends most the length of the body.

In the case of the bone-supporting component such as a bone plateincluding a head portion, the radiopaque marker extends around at leastpart (e.g., 10%, 30%, 40%, 60% or intermediate or greater amounts) ofthe contour of the head portion or head portion (e.g., when viewed froma side of the implant). Optionally, the radiopaque marker extends aroundthe entire contour of the bone plate. Optionally, the radiopaque markeris on the side of the bone plate facing outward after implantation.Optionally, the contour marker is within 1 mm or 0.5 mm, of the outercounter. Optionally, a marker indicating the projection of the implantis provided as well, for example, a circle or a square, or anarrangement of markers whose distortion indicates if the implant isviewed from a correct direction.

In some embodiments of the invention, the markers are formed of metalwires, for example, tantalum, gold, or platinum or similar embeddedinside the components. For example a tantalum wire having diameter of0.2-0.5 mm is suitable.

Optionally or alternatively, the marker comprises a plurality ofmarkers, for example, beads or wire sections. Optionally, such markersare used to indicate pre-drilled holes or slots and/or locations forprocessing.

An aspect of some embodiments of the invention pertains to abone-supporting component, in which opposite ends of fixation componentpassage include reinforcing fibers optionally having opposite U-shapedconfigurations to help reduce wear and/or breakage due to forces from afixation device.

Alternatively, the cylindrical part of the body is coated with amaterial to reduce friction between the body and the passage.Optionally, the coating is a polymer, for example Teflon. Optionally,the coating is a ceramic material, for example alumina.

In some embodiments of the invention, there is a bearing, for example, ahollow cylinder or cylinders, between the passage and the portion of thefixation component body located in the passage when the device isimplanted.

Optionally or additionally, the surface of the passage bears a metalcoating to help reduce formation of debris during implantation.

An aspect of some embodiments of the invention relates to drilling andfixation component insertion accessories, optionally provided in kitform together with one or more implants and/or fixation devices. Suchaccessories are optionally configured to be temporarily attached to theimplant components to assist a surgeon in properly positioning andanchoring the components.

In some embodiments, the accessories include one or more of a targetingdevice for drilling holes to anchor the head of a bone plate, a drillguide for holes to anchor bone nails, and fixation component insertionguides, or accessories that incorporate one or more of the describedfunctions. Optionally, the accessories are formed of metal, or of aradiolucent material, for example, a polymer. Optionally, the polymer isfiber-reinforced.

In an exemplary embodiment of the invention, the accessories areconfigured to be disposable after a single use, for example, due to wearor difficulty in sterilization. Optionally, the accessories supplied preassembled with the implant.

In some embodiments of the invention, a bone implantation systemincludes one or more fixation components, one or more bone-supportingcomponents, and one or accessories, for example, as described above, andmay also include a bone nail insertion support apparatus that is used toshare the loads exerted on the nail-handle connection interface duringinsertion of the nail into the bone.

In an exemplary embodiment of the invention, the accessories include oneor more radiolucent drill guide, optionally configured for attachment tothe composite bone implant. Optionally, the drill guides are drilledduring or before surgery, at a desired angle of access for the drill.Optionally or alternatively, the drill guides are formed, for example,using computer-controlled 3D prototyping tools, for example, based onone or more 3D CT images.

In some embodiments of the invention, the system also may include aradiolucent drill connector, one side of which is configured forconnection to a power unit. The other side is configured for connectionto a drilling tool. Optionally, the connector includes a clutcharrangement to assure the drill bit operates only when the surgeon holdsthe power unit and intentionally engages the clutch, e.g., by pushingthe power unit toward it. Optionally, the connector (or a drill) is notstraight, so that part of the connector (or drill) is not blocking theview of an x-ray imager.

In some embodiments of the invention, the radiolucent drill is a singleuse device, having in its proximal side, handle, electric motor,battery, switch and optionally gear, and in his distal radiolucent side,radiolucent drill bit connector, and optionally right angle gear such asbevel gear or worm gear. Optionally, a radiolucent shaft transmits thetorque from the motor or the proximal gear, between the proximal and thedistal sides of the device.

An aspect of some embodiments of the invention relates to drillingpassages in the bone-supporting component and/or fractured bones duringan implant procedure while applying suction to aid in removal ofdrilling debris and/or irrigating. Optionally, a drilling instrument ortool is contained within a tube that enables suction of the drillingdebris. Optionally, the drilling tool is cannulated and suction isperformed through the cannulation. Optionally, the suction is performeddirectly through the cannulation. Optionally, the suction is performedthrough a separate tube located in the cannulation.

In some embodiments of the invention, the drilling site is irrigated,e.g., with sterile saline solution during drilling. Optionally, with acannulated drilling tool, the cannulation is used to provide theirrigation fluid, and an external tube provides the suction. Optionally,the cannulation is used to provide the suction, and an external tubeprovides the irrigation fluid. Optionally, the external tube surroundsthe drilling tool. Optionally, the external tube is completely separate,and is positioned adjacent to the drilling tool.

In some embodiments of the invention, where the drilling tool is notcannulated, separate tubes, either surrounding the drilling tool, oradjacent to it are used to supply irrigation fluid and for suction.

In some embodiments of the invention, irrigation is not employed, andsuction of drilling products is performed simultaneously from thedrilling tool cannulation (with/without an internal suction tube) andfrom an external suction tube.

The irrigation can help cool the implant and surrounding tissue whiledrilling is being performed, for example, to reduce or avoid the risk ofdamage of patient tissue and/or devices.

In some embodiments of the invention, a bone implant device includefixation components and bone-supporting components having variouscombinations of features as described above, and as described in detailbelow.

In some embodiments of the invention, implant kits include fixationcomponents and bone-supporting components and accessories having variouscombinations of features, also as described above, and as described indetail below.

Exemplary Bone Nail Embodiments:

FIG. 1 illustrates schematically in a side view, a bone-supportingcomponent of an implant, intramedullary nail 10, for example a humeralnail, connected at its proximal end 12 to an insertion handle 14.Illustrated nail 10 is configured for use in treating humeral fractures.However, it should be understood that this and other embodiments areapplicable to other intramedullary nails as well, such as nails fortibia bones, femur bones, or other bones. Typically nail 10 is betweenabout 7 and about 12 mm in diameter. In some embodiments of theinvention, the radiolucent drill is a single use device, for example,having in its proximal side, handle, optionally electric motor, optionalbattery, switch and optionally gear, and in his distal radiolucent side,radiolucent drill bit connector, and optionally right angle gear such asbevel gear or worm gear. Optionally, a radiolucent shaft transmits thetorque from the motor or the proximal gear, between the proximal and thedistal sides of the device.

The proximal region 13 of nail 10 includes two holes 15, 17 positionedin the same orientation for the insertion of screws that fix the nail tothe bone. The distal end 29 of nail 10 includes three additional holes19, 21, 23 for bone screws. Other configurations, numbers, andorientations of screw holes may alternatively be provided.

Radiopaque markers 25, 27, optionally made of tantalum or other suitablemetal, are provided near each screw hole to assist in drilling and screwplacement. These are illustrated as diametrically opposite dots, but canhave other configurations, for example, circles around the holes.Suitable radiopaque materials include tantalum, gold, platinum, or otherbiocompatible metal.

As will be understood, nail 10 is configured to be inserted into themedullary canal by the surgeon during the implant procedure with theassistance of insertion handle 14.

Insertion handle 14 is an example of a suitable device for performingthe actual insertion. Handle 14 comprises a curved portion 16 and astraight tube 18, which engages with the proximal end 12 of nail 10.Curved portion 16 is optionally formed of metal but is preferably formedof composite material to reduce interference with radiographicvisualization during implantation.

The process of insertion of nail 10 into the bone may involvemanipulation of the nail-handle assembly and thus may impose bending andtorsional forces on the nail. Therefore, an inner rod 24, optionallyformed of metal, for example, surgical grade stainless steel istemporarily installed between nail 10 and handle 14, to strengthen theconnection area for bending. Rod 24 is introduced via a cannulated nailadapter 20 which may be part of handle 14, or a separate element.

As shown in FIG. 2, rod 24 is configured to penetrate into a bore 34 atthe proximal end of the nail. Optionally the diameter of the bore 34 isin the range of 2 to 5 mm Optionally, rod 24 extends beyond the proximalhole 15 in the nail. Following nail introduction part way into the bone,the inner rod 24 is removed.

According to bench testing performed by the inventors, inner rod 24improved the bending properties of the nail-handle connection area.

FIGS. 2 and 3 are respectively enlarged sectional and perspective viewsof the proximal region 13 of the nail 10 illustrated in FIG. 1. As shownin FIGS. 2 and 3, the nail includes a threaded end-portion 30, to whichthe nail adapter 20 is connected, and a connection detail 32 at proximalend 12 having slots 40 configured to engage matching protrusions at theend of insertion tube handle tube 18 when it is connected to the nail 10(see also FIG. 3).

One or more radial slots and complementary teeth may be provided.However, according to bench testing performed by the inventors,increasing the number of the slots in the connection detail (and thecomplementary teeth at the handle end), leads to improved torquetransfer.

By way of example, as shown in FIG. 3, connection detail 32 includesseven radial slots 40 a, 40 b, 40 c, etc., although other numbers andshape of slots are also feasible. Optionally, the slots 40 arepositioned so that the distance between at least two adjacent slots 40 aand 40 b is different than the distance between other adjacent slots,thus providing only a single orientation of connecting the nail tohandle 14, and helps assure introduction of the nail into the bone inthe correct orientation.

The connection detail 32 (shown enlarged in FIGS. 2 and 3) mayoptionally be produced by machining or during the compression moldingprocess by which the composite nail is formed. Forming connection detail32 by compression molding may be advantageous in terms of costreduction.

FIG. 3 also illustrates the proximal end 12 of a composite materialhumeral nail 10. By way of example, the diameter of nail proximal region13 may be in the range of about 10 to 12 mm for a nail shaft 38 having adiameter in the range of about 7 to 9 mm. The nail is connected to itsinsertion handle via a thread (not shown) at its proximal end.

FIGS. 2 and 3 also show screw holes 15, 17. Holes 15, 17 may bethreaded, or optionally, they may be unthreaded. A radiopaque marker 36is also shown at the proximal end of the nail.

Following nail implantation, a nail cap (not shown) may be introduced(e.g., screwed) into the threaded bore 30 at nail proximal end, in orderto prevent bone growth into bore 30.

Pre-Drilled and Undrilled Bone-Supporting Component Configurations:

In FIGS. 1-3, bone nail 10 is shown with the passages for the bonescrews pre-drilled during manufacture. In some embodiments of theinvention, however, the bone nail, and also bone plates as describedbelow, are supplied undrilled, or optionally, with a few screw holes orother passageways, for example, for initial anchoring. Thereconfiguration guides facilitate formation during the implantationprocedure of passages in the bone-supporting component for the fixationcomponents or for otherwise shaping the bone-supporting component at theoptimum locations and orientations for the particular fracture andpatient anatomy. In addition, especially where small implants areinvolved, the option of not having unnecessary screw holes maycontribute to the strength of the bone-supporting components.

Optionally, undrilled bone-supporting components include built-inreconfiguration guide areas e.g., indentations or depressions in thecomponent surface that form blind grooves or slots, or blind holes orcutting lines. These built-in reconfiguration guides help preventsliding of the drilling tool, particularly as a hole is started.Optionally, the implant is provided with several such reconfigurationguides located at positions in the implant that would not compromise therequired implant biomechanical properties following drilling, forexample, along the center line of the nail shaft or bone plate.

Exemplary built-in reconfiguration guides are described further below.

Exemplary Composite Materials:

In some embodiments of the invention, bone-supporting components andfixation components as described herein are formed of fiber reinforcedpolymer matrix composites. As an example, the composite material may bea fiber-reinforced polymer matrix, in which the polymer matrix is formedof polyetherketoneketone (PEKK), polyetheretherketone (PEEK), or othersuitable polymers).

The reinforcing fibers may alternatively be formed, for example, ofcarbon or of a ceramic material, such as glass. The fibers may be of adiameter in the range of about 5 to about 10 microns for carbon fibers.Optionally, the carbon fibers are AS4, IM7, or IM10 Made by Hexcel Inc.Stamford Conn., U.S.A. Carbon fibers may optionally constitute about 60%to about 70% by volume of the composite.

Elongated components such as pegs, screws, and bone nails are optionallyformed with a core in which the reinforcing fibers run longitudinally toresist mainly bending loads, and a sleeve enclosing the core, formed ofone or more spirally wound layers for resisting mainly torsional loads.The core diameter is selected according the specific application of aparticular implant.

Optionally, the sleeve is formed of two or more oppositely wound helicallayers, for example, in which adjacent layers are wound at ±45 degreesrelative to the core longitudinal axis. Winding over the core at ±45degrees provides for maximal torsional stiffness (compared to otherdegrees of winding), as the fiber strain in those configurations ismaximal per torsional angle of the nail.

Optionally, an additional outer layer is provided, as described below.

According to some embodiments, the core and the sleeve are constructedfrom pre-impregnated (prepreg) tapes of carbon fiber-reinforced polymer,preferably a thermoplastic polymer such as PEEK.

The prepreg tapes are available in the form of straight layers, duringwinding of each prepreg tape, the radius of curvature of the tapechanges to conform to the winding diameter of the core. During winding,the filaments at the inner portion of the tape (i.e., with the smallestradius) become slightly folded. Thus, upon application of torsion, thefilaments at the outer portion of the tape are stretched and can resistthe torsional moment, while the inner filaments are not yet stretched.The inner filaments are only under tension upon exertion of highertorsional moments. In an embodiment of the invention, reducing thethickness (height) of the prepreg tape results in winding in whichsubstantially more fibers are stretched earlier (i.e., upon applicationof lower torsional moment), and thus more efficient torsional stiffnessis achieved. Optionally the thickness of the prepreg for winding is inthe range of 0.05 to 0.2 mm, preferably 0.1 mm or less.

In an embodiment, the entire thickness of the winding (sleeve) remainssubstantially the same, while the thickness of each wound tape isdecreased and the number of wound tapes is increased. Alternatively,decreasing the tape thickness, and thus improving the torsionalstiffness, enables reducing the thickness of the winding sleeve on onehand, and increasing the diameter of the bone implant devicelongitudinal core (without increasing the diameter of the entiredevice), on the other hand. Therefore, this feature may contribute notonly to the torsional stiffness of the device, but also to its bendingperformance.

The tapes intended for winding over a component core may also bemanufactured as a helix, with the same (or approximate) radius ofcurvature of the required final winding radius.

Further exemplary details concerning the nature and use of prepreg tapesmay be found in International Application PCT/IB2010/050225 which isincorporated herein by reference.

In some embodiments of the invention, at least some of the individualreinforcing fibers are at least partially coated. Such a coating canimprove the strength of the implant, and/or may improve adherence of thepolymer to the reinforcing fiber element. In an exemplary embodiment ofthe invention, a metal coating, for example, a titanium coating is used.In another exemplary embodiment of the invention, carbon with differentcrystalline properties (e.g., diamond, graphite, amorphous carbon,etc.), is used to coat the reinforcing fibers within the polymer matrixand/or the entire implant (for example, a diamond-like carbon coating).In an exemplary embodiment of the invention, the coating layer thicknessis, for instance, less than 0.1 micron. In an embodiment, the coatingtotals in a relatively small amount of material, which does notadversely affect the implant properties under MR/CT imaging.

In some embodiments of the invention, different types of carbon fibersmay be placed in different places in the implant to get advantage ofdifferent properties and/or different cost of the fibers. For example,fiber IM10 is stronger in tension 6,964 MPa compared to fiber AS4: 4,500MPa but fiber IM10 is also less flexible having tensile module of 303GPa relative to 231 GPa of fiber AS4. Accordingly in implant such as butnot limited to nail, screw or plate, to get more flexibility for bendingfiber type AS4 may be used in the core, and to get more torsionalstiffness, IM10 will be used for the winding.

Typically, the polymer matrix is the weakest element in the composite.Optionally, the matrix may therefore include chopped fibers of carbon orother reinforcing material, which may improve bending performance.Optionally, the chopped fibers have different orientations in thematrix. Optionally, the chopped fibers are of various lengths within arange of about 0.1 to about 3 mm, and may constitute between about 1%and aboutl0% of the composite volume. The chopped fibers may be embeddedinto the prepreg tape, during manufacturing of the prepreg.

Alternatively chopped fibers may be added between the layers of theprepreg. Optionally, polymer material may be removed from the prepregtape by heat and pressure.

Prepreg tapes are normally available in thickness not smaller than 0.2mm. When calculating the strain required to initiate tension in thefilaments at the inner portion of a tape with thickness of 0.2 mm whichis helically wound (at 45 degrees) over a longitudinal core having adiameter of 8.5 mm, the strain is 2.3%. The strain at failure for acarbon fiber such as HEXCEL IM7 is about 1.9%. This means that for atape of 0.2 mm thickness, the fibers in the outer surface of the tapeare torn while the inner layer of the tape has not yet straightened andthus has not yet participated in the winding resistance to torsion.

Similar calculation for tape thicknesses of 0.1 mm and 0.05 mm resultsin strain values of 1.1% and 0.58%, respectively. In an embodiment ofthe invention, the ratio between the diameter of the device longitudinalcore and the thickness of the helical tape is larger than 40, optionallylarger than 70, optionally larger than 100 or 150. Strain at failure isthe strain at which the fiber breaks. Using small thickness prepregtape, and more windings, will share the stress along all the crosssection area of the tape, and add torsional strength.

Exemplary Bone Screw and/or Peg Embodiments:

FIG. 4 is a generally side perspective view that illustrates an exampleof a fixation component 100 which may be used as a peg or screw toanchor a bone-supporting component such as a bone plate, or as a bonescrew for a bone nail. One or more pegs or screws 100 are configured toextend through passages in a bone plate, and into holes drilled in thebone under the plate, as described below.

Bone screws and pegs are optionally formed of the same materials as thebone nails described in connection with FIGS. 1-3, and/or by a similarcompression molding process, except that pegs do not need a sleeve toresist torsional forces.

Optionally, the composite material bone screw also comprises materialthat reduces the friction with the bone. Examples of such material areSiO2, PTFE, etc. The material may be added as powder, particles and/orother forms. Metal particles, such as titanium, may also be added toincrease the device strength and to provide visualization under imaging(e.g., fluoroscopy).

FIG. 5 illustrates in a schematic sectional view use of component 100specifically as a bone screw for an intramedullary nail 106. Bone screw100 is configured to attach to a bone 104 on a proximal side 104 a, toextend through a passage 105 in a bone nail 106, and to attach to thebone at 104 b on the side opposite to the bone nail. The passage 105 maybe round as shown in FIGS. 1-3, or one or more passages may also beformed as longitudinal slots (no shown) to facilitate longitudinalpositioning, for example, of a bone nail, which is then optionallyfirmly anchored by screws in round holes.

Referring still to FIGS. 4 and 5, fixation component 100 includes anattachment element, e.g., a threaded proximal end 102, configured toengage with the outer surface of a bone plate, or the proximal side 104a of a bone 104 in which a bone nail 106 has been implanted.

As further illustrated in FIGS. 4 and 5, the distal end 112 of body 108is also optionally threaded. In the case of a bone screw, threads 112engage with bone 104 on the distal side 114 of bone nail 106 at 104 b(see FIG. 5) to immobilize bone nail 106 in the desired location andorientation, which are determined by the surgeon when the bone isdrilled. Optionally, in the case of a bone peg, distal end 112 may beunthreaded. Optionally, threaded proximal end 102 may be replaced orsupplemented by a locking element on body 108 that engages with thepassages in the bone nail.

At the proximal end 116 of fixation component 100, a coupling element118 is provided for engaging an insertion tool. Coupling element 118 isshown as a hexagonal recess 120 in a screw head 121, but any othersuitable and desired shape, for example, Phillips head, axial crown,slotted, hexalobe, etc. may alternatively be provided. Recess 120 mayalternatively be internally and/or externally threaded. As will beunderstood, the configuration of recess 120 optionally matches theconnation end of the insertion tool

Referring still to FIGS. 4 and 5, the head 121 and body 108 may be anintegral structure formed, for example, by compression molding of thefiber-reinforced polymer composite material. Alternatively, head 121 maybe formed a suitable biocompatible metal such as stainless steel ortitanium into which composite body 108 is molded.

Friction forces associated with body loads can sometimes lead toabrasion at interfaces between the bone nail and the bone screw whichproduces polymer and/or fiber debris. To minimize or avoid this, thefixation components are advantageously constructed to reduce frictionbetween the fixation components and the passages in the bone-supportingcomponents. Alternatively or additionally, the components may befabricated to have sufficient strength to resist the forces at theinterface.

One way to accomplish this is shown in FIG. 5, in which one or moresleeves 122 are fitted into passage 105 in bone nail 106. Sleeve 122 maybe used to change the type of friction in the interface from slidingfriction to rolling friction. This arrangement is particularly, but notexclusively, suitable for bone nails and bone screws, where the bonescrews are anchored at one or both ends in the bone.

Additionally, or in the case of pegs, alternatively, resilient lockingelements may be provided. These are coupled to the body, and configuredto engage the passages only over a small area and thereby reduce wearand creation of debris.

Locking elements may take various forms, among which are spring elementscoupled to the fixation component, and constructed and configured toexpand radially to engage with the passage upon insertion.

One suitable arrangement is shown in FIG. 4. As illustrated, at thedistal end of proximal threaded portion 102, there is a groove 124 inwhich a resilient split ring element 126 is positioned. This can beformed of any suitably strong and resilient material, including but notlimited to a reinforced polymer composite material. As will beunderstood, split ring 126 is compressed in the passage in thebone-supporting component so that the restoring force anchors thefixation component.

Another suitable arrangement is shown in FIG. 6A. Here, fixationcomponent 300 is free of threads in its proximal region 304 and isthreaded only at its distal region 306. Locking element 308, also in theform of a resilient split ring, is fitted in a groove 320 at theproximal end of the threaded portion 306.

Another locking arrangement for use with pegs and/or bone screws isillustrated in FIGS. 6B-6D. In contrast to fixation components 100 and300 shown in FIGS. 4 and 6A, fixation component 300A includes anenlarged thread 309 installed in bone-supporting component schematicallyillustrated at 311. FIG. 6C is a cut-away view of FIG. 6B, and FIG. 6Dis an enlarged sectional view of FIG. 6C.

As illustrated in FIG. 6D, a thread 309 at the proximal end of threadedportion 306 is made oversize relative to the other threads and relativeto the passage 310 in bone-supporting components 311 so that thecomposite material of the enlarged thread(s) must compress as it isinstalled through passage 310.

In some other embodiments, a bone screw may be metal-coated, or coatedwith a polymer such as a bioresorbable or biodegradable material toreduce wear during implantation, or for other purposes, as in the caseof bone nails, and employing the same coating materials.

For example, coating may be provided to strengthen and/or improve thehardness of the implant. In an exemplary embodiment of the invention,the screw is coated with one of the following materials: titaniumnitride (TiN) [E. Lugscheider, S. Barwulf, M. Riester, H. Hilgers,Magnetron sputtered titanium nitride thin films on thermoplasticpolymers, Surface and Coatings Technology 116-119 (1999) 1172-1178; andH. S. Kim, H. J. Jung Kim, Detorque force of TiN-coated abutment screwwith various coating thickness after repeated closing and opening, JKorean Acad Prosthodont: Volume 45, Number 6, 2007], titanium aluminumnitride (Ti—Al—N), diamond like carbon (DLC), ceramic material or othersuitable material. In an embodiment of the invention, the coating isperformed using physical vapor deposition (PVD) technique[Rahamathunnisa Muhammad Azam, Mari Tanttari, Tommi Kaariainen, DavidCameron, Coatings on Composites, Lappeenranta University of Technology,Faculty of Technology, Department of Mechanical Engineering, ResearchReport No. 74, ISBN 978-952-214-504-8, ISSN 1459-2932, Mikkeli 2007],optionally following preparation of the surface of the implant (e.g.,grid blast, bombardment of argon ionized ions, etc.). In an embodimentof the invention, more than one material is used for the coating, forexample a first coating layer of titanium and a second coating layer ofceramic material. In an exemplary embodiment of the invention, thethickness of the coating layer is in the range of a few microns. In anembodiment of the invention, coating of the bone implant is conducted inorder to improve the implant osteo-conductive and/or osteo-inductiveproperties, thus to enhance implant ability to integrate in the bone andto support bone ingrowth. Such coating may be, for example, poroustitanium or hydroxyapatite (HA). In an embodiment, the coating is addedusing a vacuum plasma spray (VPS) technique, optionally followingpreparation of the surface of the implant [as described, for example, inS. W. Ha, A. Gisep, J. Mayer, E. Wintermantel, H. Gruner, M. Wieland,Topographical characterization and microstructural interface analysis ofvacuum-plasma-sprayed titanium and hydroxyapatite coatings on carbonfibre-reinforced poly(etheretherketone), Journal of Materials Science:Materials In Medicine 8 (1997) 891-896; and S. Beauvais, O. Decaux,Plasma Sprayed Biocompatible Coatings on PEEK Implants].

With any of the spring locking arrangements described, and thearrangement of FIGS. 6A-6D, a mechanism is optionally provided forremoving the fixation component if necessary. One suitable way is shownin FIG. 6A. Here, head 314 includes a plurality of notches 316 at theproximal end 318 of head 314 in which a removal tool may be engaged.

FIGS. 7A-7D illustrate other exemplary embodiments of composite materialbone screws. FIG. 7A shows a side elevation of a bone screw 140; FIG. 7Bis a proximal end perspective view of FIG. 7A. FIGS. 7C-7D are schematicsectional views of the distal region 141 of bone screw 140.

Screw 140 comprises a head 142 at its proximal end, with connectionmeans to engage with insertion/removal instruments (not shown).Connection means may be of any conventional shape, for example, aninternally or externally threaded hexagon, Phillips head, axial crown,slotted, hexalobe, etc. The hexalobe configuration may be advantageousin resisting damage due to application of torsion by the insertiondevice.

The distal end 144 of screw 140 is tapered 144 and comprises cuttingedges 150 to provide for self-tapping. The screw 140 also comprisesthread 146 at a desired pitch along its length. The screw 140 is made,for example, from a fiber reinforced polymer, a material that isradiolucent under imaging such as fluoroscopy, as described in moredetail below.

FIG. 7B illustrates a screw that comprises a core 112 made of relativelystraight elongated fibers 114 within polymer matrix 116. In an exemplaryembodiment of the invention, the screw is manufacture in two mainsteps—compression molding, during which a composite material rod isgenerated, and machining, during which the screw thread 118 is created.As can be seen in the figure, the fibers in the thread 120 are cut dueto the machining process. Having only straight longitudinal reinforcingfilaments at its core contributes to the screw bending properties. Onthe other hand, the short, non-sequential fibers at the screw threadcompromise the thread resistance to shear forces. Therefore, thiscombination of screw features may be beneficial for screw applicationsthat mainly require bending strength, such as screw intended tointerlock an intramedullary nail.

FIG. 7C illustrates a screw that is entirely (i.e., including its thread122) produced by compression molding. In some embodiments, a fiberreinforced polymer material, for example in the form a rod, is pressed(under heat and pressure) into a mold that forces the material to foldat and into designated areas (e.g., the thread areas), thus creating athread 122. This optionally results in a composite material screw thatcomprises folds of the elongate fibers 124 and fibers 126. This screwconfiguration may be beneficial for applications that require highpullout strength forces but less bending strength, for example, screwsused with bone plates, as described below.

FIG. 7D illustrates a screw that comprises a core 128 made of relativelystraight elongated fibers 130 within polymer matrix 132, produced, forexample, by compression molding. Over core 128, a helically winding 134in one direction of fiber reinforced polymer is added, optionally in amanner in which winding pitch is equivalent with the desired screwpitch. Optionally, the helical winding 134 is made of prepreg tape/s offiber-reinforced polymer, so that tape width is compatible with thedesired width of the screw teeth. Optionally, the screw is furthermachined to produce the desired configuration of the thread teeth 136.Optionally, a profile winding 134, for example that has a relativelytriangular cross section is helically wound around the core 128. Such athread may be advantageous, for instance, upon threading of the screwinto the cortical bone.

Optionally, in embodiments illustrated in FIG. 7D, two helically woundtapes may be employed. Optionally, one is wound clockwise and the othercounterclockwise for example, at ±45 degrees relative to thelongitudinal axis of the core.

When assessing the above-described screw designs, it is expected that ascrew which comprises a core of straight longitudinal reinforcingfilaments and machined thread, may be beneficial for applicationsrequiring mainly bending strength, such as for screws intended to lockintramedullary nails to the bone.

The screw produced by axially pressing comprises folded reinforcingfibers in its core, and thus may have lower bending performance,however, the resistance of its thread to shear forces may be enhanced(as the reinforcing fibers at the thread are not damaged duringmanufacturing, and therefore may be preferred when high pullout strengthis required). This screw design may be preferred, for example, forscrews intended to lock plates to the bone (where screw pullout from thebone is the failure mode).

The screw thread created with profile winding is expected to beadvantageous during threading of the screw into the cortical bone, asthe orientation of the fibers in the thread component in this screwdesign matches the thread pitch, and thus provides for a strengthenedthread with potential for less wear upon screw threading.

Reference is now made to FIGS. 8A-8C, which schematically illustrate abone screw 160 having a separate distal end component 162 made of amaterial that is harder than body 164 of the screw 160 and optionallyharder than cortical bone. FIG. 8A illustrates assembled bone screw 160,while FIGS. 8B and 8C illustrate the bone screw components 164 and 162,respectively, prior to their assembly.

The distal end component 162 may optionally be made of ceramic material,such as zirconia which also does not interfere during MRI, or a metalsuch as titanium. Screw body 164 is formed from fiber-reinforcedcomposite material as described above. Optionally, the body is formedusing the distal end as a mould.

Enhanced distal-end hardness may be useful to improve self-tappingcapability, and/or to reduce the possibility of damage to the distal endduring screw introduction into the bone.

As shown in FIGS. 8B and 8C, the interface 166 between the distal endcomponent 162 and the screw body 164 is optionally configured to providefor torsion transferring while preventing the distal end component 162from tearing off the screw body 164. Interface 166 is shown ashexagonal, but optionally, other non-circular geometric shapes may beemployed.

Optionally or additionally, distal end component 162 includes undercutportion in the internal side of this bore to help assure firm connectionof the distal end component 162 to the screw body 164. By melting thecomposite into the undercut, 162 will be axially locked into 164.

FIG. 9 illustrates another embodiment of a bone screw 170 in which adistal end 172 exhibits enhanced hardness and self-tapping capability.Here, distal end 172 includes one or more inserts, one of which is shownat 174, that serve as the thread-cutting tool. Insert(s) 174 are made ofmaterial with higher hardness than that of the rest of the screw andthan that of the cortical bone, for example ceramic or metal material.Connection of the insert to the screw is achieved using adhesion meansand/or (optionally) a non-circular geometric connection that preventstear-off of the insert from the screw.

FIGS. 10A-10D schematically illustrate other embodiments of a compositematerial screw exhibiting enhanced hardness. FIG. 10A is a schematiclongitudinal cross-section of one such embodiment. Optionally, as shownin FIG. 10A, in cases where the coating material has a limitedelongation before break, the coating over screw 250 is not continuous,but rather limited to the crown portions of threaded teeth 254, i.e.,the thread portions that penetrate into the bone, while the root areas256 between the teeth are not coated.

Discontinuous coating may be also applicable to other portions of acomposite implant.

FIG. 10B is a side elevation view of a screw that is a variation of thescrew of FIG. 10A, generally labeled 280. FIG. 10C is a cross-section ofa FIG. 10B taken along line A-A. FIG. 10D is an enlarged view of area Bin FIG. 10C.

Screw 280 differs from screw 250 in that the entire length of screw 280is covered by a coating 282. This may be desirable to increase thehardness of all the screw parts that may be in contact with bone.Optionally, the coatings of root portions 284 between the threads areoverlapped, as indicated at 286, for example, by extensions of thecoatings of the adjacent crown portions of the thread, or by overlappingthe tape as it is wound over the threads. Optionally after winding themetal tape with overlap 286, the internal and external side of theoverlap may be welded at least partially along the spiral overlap.Optionally the tape is welded using a pulsed laser or a continuous laserbeam.

FIG. 11 schematically illustrates a portion of a proximal femur implant180, including the stem 182 of an intramedullary femoral nail 183, and aleg screw 184. The nail 182 is inserted into the medullary canal of thefemoral bone, and the leg screw 184 is introduced, via a passage 188 inthe nail 182, into the femoral neck and head of the bone. The proximalfemur implant 180 is intended to treat or help prevent fractures in theproximal area of a femoral bone. The components of implant 180 are madeof a fiber reinforced polymer composite material, optionally includingother materials, such as metal (for example, titanium), and/or arecoated with a non-composite material as described above.

At its proximal end 186, nail 183 comprises a connector, e.g., aninternally threaded portion, configured to engage with an insertiontool, and, after insertion, to receive an end cap to seal the proximalend and prevent bone ingrowth.

Along its distal region 185, nail stem 182 may be tapered. In itsproximal region, in addition to passage 188 for bone screw 194, theremay be provided one or more additional passages for additional bonescrews or bone pins. These may be oriented transversely relative to nailstem 182, and function to lock the nail to the bone and/or to provideadditional rotational stability.

Passage 188 is threaded, along at least part of its length, shown at190, which is configured to engage a complementary thread 192 at theproximal end 194 of the leg screw 184. The distal end 196 of the legscrew 184, which is inserted into the femoral head, is threaded at 198,to allow firm fixation within the cancellous femoral head. The thread198 may be self-tapping. Optionally, the distal thread 198 and theproximal thread 192 of the leg screw 184 have the same pitch. The legscrew 184 may be cannulated (not shown in the figure), to allow itsintroduction into the bone over a guide wire. At proximal end 194, theleg screw 184 comprises a connector (not shown in the figure),configured to engage with the screw insertion tool. Optionally thread198 may be coated with metal.

The different threads of the implant 180 may be produced using variousprocesses, such as machining, axial pressing, and/or profile winding, asin previously described embodiments.

FIGS. 12A and 12B are side elevation and longitudinal cross-sectionviews, respectively, representative of some embodiments of a compositematerial proximal femur implant, generally illustrated at 200. Implant200 comprises an intramedullary femoral nail 202, and leg screw 204which is inserted into the femoral neck and head through a passage 212.Implant 200 also includes a sleeve 206, located in passage 212 betweennail 202 and leg screw 204.

At its proximal end 208, nail 202 includes a coupling element 210element similar to the one described in FIG. 3 configured to engage aninsertion tool. In some embodiments, proximal end 208 is internallythreaded to receive an end nail cap as in the embodiments described inconnection with FIG. 11.

Along its distal region, nail 202 may be tapered as in FIG. 11. Passage212, at least along part of its length optionally includes a threadedportion 214 configured to engage a matching thread on the outer surfaceof the sleeve 206. Sleeve 206 enables sliding of the leg screw 204 inrelation to the nail 202. This arrangement is intended to prevent aphenomenon called cut-out, referring to the subsidence of the femoralhead and protrusion of the leg screw out of the femoral head.

The sliding of the leg screw 204 in sleeve may optionally be limited,for instance by a tool inserted from nail proximal end 208 and engages alocking element 216 that limits the leg screw 204 movement to apre-defined travel. Locking screw 216 is passing through a window insleeve 206, and enters a slot in the leg screw 204. The length of theslot limits the sliding.

Reference is now made to FIGS. 13A and 13B, which are side elevation andlongitudinal cross-sectional views, respectively, of a compositematerial proximal femur implant 230. The implant 230 comprises anintramedullary femoral nail 232, a leg screw 234 and a sleeve 236,located between the nail 232 and the leg screw 234. Implant 230 isgenerally similar to implant 200 described in connection with FIGS. 12Aand 12B, and the details will not be repeated in the interest ofbrevity.

Implant 230 differs from implant 200 mainly in that sleeve 236 is longerthan nail passage 242. Optionally, the sleeve 236 protrudes from bothends of the nail passage 242. Having a longer sleeve may be advantageousin some embodiments, as the leg screw 234 experiences lower bendingmoment in this configuration.

Various embodiments of implants 180, 200, and 230 share severalfeatures. For example, one or more of the following features may beprovided in the implants described herein or in other compositeimplants:

a) leg screws 184, 204, and 234 may be cannulated, to allow introductioninto the bone over a guide wire;

b) at their respective proximal ends, the leg screws include connectorsconfigured to engage with screw insertion tools;

c) implants 180, 200, and 230 are made of a composite material, asdetailed above, and may optionally include metal components and/or maybe partially or completely coated with metal or other non-compositematerial;

d) sleeves 216 and 236 may be made of metal such as titanium, ceramicmaterial, or composite material with reinforcing fibers oriented and/orconfigured to carry the load exerted on the bone, as described inconnection with FIGS. 12A and 12B.

e) nails 183, 202, and 232 may include additional passages (not shown),configured to accept anti-rotational pins. These may, for example, be ofsmaller diameter than the passages for the bone screws, and may belocated parallel to- and above the respective leg screw passages.

f) the longitudinal stem of the nail may be expanded following itsintroduction into the medullary bone canal, in a manner that allowsabutment of at least part of nail outer surface to the inner wall of thebone canal for example, in a similar manner to that described in WO0154598 (U.S. Pat. No. 6,127,597).

g) the implants may include at least one radiopaque marker e.g., atantalum thread, ring, dot, pin, etc. (not shown), as discussedhereinafter. Optionally, a passageway, for example, for a guide wire ismade or includes a radiolucent material, for example, in the form of awire or hollow tube.

FIGS. 14A and B illustrate a possible solution to a reinforcementproblem that may exist due to high local stresses causing deformationfor example, in the stem of a proximal femur nail in applications suchas illustrated in FIGS. 11-13. FIG. 14A shows a sectional view of theproximal end 502 of nail 500. FIG. 14B shows a side view of FIG. 14A,i.e., rotated 90 degrees.

Stress can be especially severe in the edges of the leg screw hole ofthe stem, due to the high moment applied by the leg screw on the hole.Orienting the reinforcing fibers longitudinally or helically does noteliminate the deformation.

According to some embodiments of the invention the problem is alleviatedby orienting the reinforcing fibers in a way that converts thecompression reaction into tension of the fibers in the stem. FIG. 14Ashows the points of greatest stress 504 and 506 due to bending of bonescrew 508. At these locations, the reinforcing elements 510 and 512 areconfigured in a U-shape and an opposed U-shape at ends 514 and 516,respectively, of passage 518. Reinforcing elements 510 and 512 areoriented preferably in planes perpendicular to the main axis of thescrew 508, where leg screw 508 bears most forcefully in passage 518. Inthis way, the compression reaction due to the leg screw 508 load isconverted into tension of the fibers.

FIG. 15 is a schematic side view of a fixation component 560 thatillustrates a solution to another reinforcement problem that may existdue torsional stresses of a fiber-reinforced head 562 of a bone screw.The torsional forces resulting during insertion are supported by addinga ring 564 of circumferentially or spirally wound reinforcing fibers566.

FIG. 16A is a side elevation view, and FIGS. 16B and 16C arelongitudinal cross-sectional views taken along line A-A in FIG. 16A,that illustrate two options for radiopaque marking of a radiolucentfixation component such as a bone screw generally denoted at 440 in FIG.16A. To provide for visualization of the screw under fluoroscopy duringthe implantation procedure, and/or post-operative follow-up, a metalwire 452 is incorporated into the screw along its longitudinal axis (seeFIG. 16B). Optionally, the wire is made of tantalum.

Alternatively, as illustrated in FIG. 16C, two radiopaque wires or pins454 and 456, are provided only at the proximal and distal ends,respectively, of screw 440. These, too, may optionally be formed oftantalum.

It is to be understood that other shapes, e.g., dots or rings, anddifferent sizes, locations and materials may be applicable for markingthe radiolucent bone screw.

It should be noted that if some of the reinforcing filaments of the boneimplant are at least partially coated, adding a radiopaque marker toprovide visualization of the radiolucent implant under fluoroscopyduring insertion may not be necessary. It may be desirable, however, tolimit the coating so that it does not interfere with post-operativevisualization.

FIGS. 17A and B respectively illustrate top perspective and sidesectional views of a bone plate 600 demonstrating several features, oneor more of which may be provided in one or more embodiments ofbone-supporting components, i.e., bone nails and bone plates.

Bone plate 600 includes a head portion 602 and a stem or shaft portion604, both of which are configured and sized according to the particularbone for which plate 600 will be used. In the Figure, a proximal Humerusplate is shown. Head portion 602 includes an array of bores 606 and stemportion 604 includes a line of bores 608 spaced longitudinally along amidline of the stem. These are configured to receive the fixationcomponents. The number and spacing of bores 606 and 608 are optionallydetermined, for example, like the size and configuration of the plateitself, according to the particular bone for which the plate will beused.

Stem portion 604 optionally includes a line of transversely extendingdepressions 610. The purpose of depressions 610 is to reduce the area ofcontact between the bone and the plate. Reduction of the contact areamay also assist in maintaining the integrity of the fixation. In someembodiments, this may also be achieved by the spacing and size of thedepressions.

According to some embodiments of the invention, bone-supportingcomponents, including bone nails and bone plates, are manufactured andprovided to the user without some or all screw holes. Instead, the holesare formed by the surgeon during the implantation. As shown in FIGS. 17Aand 17B, implant 600 may include one or more blind bores or grooves orother indentation and/or protrusions in the stem, which do not penetratethe entire implant thickness. For example, they may extend 10 to 20% ofthe thickness of the plate stem. Alternatively, they may extend more,for example, 50%, 70% or more, for example, being narrow-diameter holes.

The blind grooves cooperate with drilling tool and fixation componentinsertion accessories as described below, and help to position and gripthe drilling device while the surgeon drills holes through the grooves.This allows the surgeon to insert the fixation components devices in theoptimal locations and directions/angles. Since these may vary from caseto case, the surgeon has the flexibility to address the need of eachcase individually and to provide for more efficient and safe fixation.In addition, where small implants are involved, the option to have onlythe number of screw holes for the particular application may contributeto the strength of the implant. Optionally, an attachment location, forexample, a notch or hole is provided for attaching an adjustable toolguide to help guide a tool during reconfiguration of the implant (e.g.,by drilling or cutting).

In FIGS. 17A and 17B, the blind bores in stem 604 are representedschematically at 606 as circular, but in some embodiments, there may beprovided a different shape that can keep the drill bit in place duringdrilling Optionally, the implant is provided with several such grooves,which are located at positions and/or in directions of the implant thatdo would not compromise the required implant biomechanical propertiesfollowing drilling.

Optionally, the bone implants are manufactured and provided to the userwith at least one screw hole, while the other required screw holes arecreated during the surgery.

In some embodiments of the invention, bone nails are also manufacturedwith a longitudinally extending row or other suitable arrangement ofblind grooves, either round or elongated as described above inconnection with FIGS. 17A and 17B. It is also to be understood that bothbone nails and plates may be provided with pre-drilled through-holes (asin the embodiments described in connection with FIGS. 2 and 3) in someembodiments of the invention.

Also in some embodiments, through-holes may be threaded (not shown) forattachment of accessories used during drilling and fixation-componentinsertion, and/or for locking the fixation component head to thebone-supporting component as now to be described.

Referring now to FIG. 18, there is shown a bone plate 640, including ahead, 642, and a stem or shaft 643. The figure also illustrates atargeting guide 652, and a drill sleeve 656. Stem 643 of bone plate 640includes round bores 644 and elongated slots 650. These may be blind, orextend though the plate as previously described.

Targeting guide 652 is a drilling accessory which may be used to helpdrill holes in head 642 and/or the underlying bone for receiving one ormore fixation devices. Targeting guide 652 includes an array of holes,some of which may be oriented obliquely to bone head 642. Targetingguide 652 is attached to head 642 by one or more targeting screws 654,which are held in place by threads (not shown), Optionally the targetingguide 652 has one pin (not shown), that enter into a hole in theimplant, in addition to the screw 654.

By using targeting guide 652 made of polymer, with implant made ofcomposite material, during the surgery it is possible to see underfluoroscopy very clear view of the fracture, and reduce it moreaccurately, and place the screw more accurately. Optionally targetingguide 652 made of polymer such as PEEK. Optionally targeting guide 652is supplied pre-assembled on the implant. Optionally targeting guide 652is intended for single use.

FIG. 19 shows further details of drill sleeve 656. This is an accessoryfor use in drilling holes for fixation components to be inserted in thestem 642 of a bone plate 640. Drill sleeve includes a lower portion 658configured to be received in one of the bores 644 and 650 in bone platestem 642. This may optionally be threaded to match complementary threadsin one of the circular bores 644, or may be dimensioned for a frictionfit.

Drill sleeve 656 also includes a skirt or shoulder portion 660 thatlimits insertion depth into the bore.

FIG. 19 also shows a drill sleeve holder 662 to assist in insertion andremoval of drill sleeve 656. This includes a handle 664, the distal endof which includes a fitting 666 configured to engage a complementarybore 668 in drill sleeve 656.

FIGS. 20A and 20B illustrate another drill sleeve 670. According to someembodiments of the invention. These are top perspective and verticalsectional views respectively. Drill sleeve 670 differs from drill sleeve656 of FIG. 19 in that it includes an elongated portion 672 and a knob674 at its proximal end to facilitate handling the device. The distalend 678 of elongated portion 672 (see FIG. 20B) is threaded to engagecomplementary threads (not shown) in one of the bores 644 in bone platestem 642.

Elongated portion 672 may take various forms in embodiments of theinvention. The form illustrated in FIGS. 20A and 20B is a spiral spring676 which allows torque transfer from the knob 674 to screw and unscrewdistal part 678, while preventing transfer of bending forces, thusreducing the chance of damage to the bores or the internal threads.

Optionally, elongated portion 672 may be formed of oppositely woundconcentric springs, i.e., one spiraled clockwise, and the other spiraledcounterclockwise.

FIG. 21 illustrates a combined targeting guide and fixation deviceinsertion accessory 680. This includes three components: an insertionguide 682 for insertion of a fixation-component, a drill guide sleeve684, and a K-wire sleeve 686. A K-wire is optionally used beforedrilling, to get idea about the drilling direction.

In use, accessory 680 is assembled with insertion guide 682 and drillguide 684 connected together and inserted into a hole in a targetingdevice 652.

All the accessories described in connection with FIGS. 18-21 may beformed of metal or of a polymer, optionally a fiber-reinforced polymercomposite.

It should also be understood that other configurations of drill andfixation-device insertion guide accessories, including such accessoriesthat are configured for disposal after a single use, are also within thescope of the invention. It should also be understood that, in someembodiments of the invention, implantation may be done without using thedrill sleeve as described above.

FIGS. 22A and 22B are schematic top views that illustrate ways toprovide for visualization of bone plates under fluoroscopy duringimplantation and/or at follow-up in some embodiments of the invention.In FIG. 22A, a bone plate 700 is shown that includes a head 702 and anelongated stem portion 704. A radiopaque marker shown here as a seriesof short marginal wire sections 706 extends around the edges of head 702and the distal end 708 of stem portion 704.

FIG. 22B shows a variation in which the wire sections 710 extend alongthe entire contour of bone plate 700.

The markings may take optionally various forms, for example, twolongitudinally continuous wire sections formed of tantalum or othersuitable metal in the embodiment of FIG. 22A, or a single continuousmarginal wire in the case of the embodiment of FIG. 22B. For example,tantalum wire having diameter of about 0.2 to about 0.5 mm may be used,and located about 1 mm from the implant edge. Use of a radiolucent boneplate allows an advantageous method of assisting the surgeon inpositioning of bone fragments for optimum healing, and following theprogress of post-operative healing.

FIGS. 23A and 23B are assembled and partially exploded perspective viewsof some embodiments of the invention illustrating a design for a bonenail insertion support apparatus 750 which may be used to share theloads exerted on the nail-handle connection area during insertion of thenail into the bone.

In FIG. 23A, insertion apparatus 750 is shown enclosing the connectioninterface between a bone nail 752 and a handle tube 754. Insertionapparatus 750 includes a housing comprised of two complementary parts756 and 758 that cover the connection interface. These are optionallyconnected to each other by a screw 760 (refer also to FIG. 23B), that isreceived in holes 762, 764 in parts 756 and 758, respectively, as wellthrough the lower hole 766 at the proximal end of nail 752. Hole 764 hasa thread and screw 760 is inserted through hole 762, and nail hole 766and threaded into hole 764. The latter will also be used for insertionof a fixation-component. Optionally, the screw 760 is provided alreadyconnected to one of the parts 756. A pin 768 in the other part 758 isconfigured to be inserted into a hole in the handle tube 769. Torque istransmitted through pin 768 to part 758, and then to the screw 760 andnail 752. In this manner, part of the torque is transmitted from thehandle to the nail.

Optionally, insertion apparatus 750 may also be configured to enable theuse of one insertion apparatus with nails of different diameters.

During operation, the nail 752 is connected to the handle tube 754 viathe nail adapter (not shown in the figure), and then apparatus 750 isassembled over the nail-handle connection area. Following introductionof most of the nail into the bone, the insertion apparatus isdisconnected and removed to allow introduction of the rest of the nailinto the bone.

FIGS. 24A and 24B are, respectively, assembled and partially explodedviews of some embodiments of another nail installation device 770. Asshown, installation device 770 is similar to insertion device 750,except that the complementary parts 772 and 774 configured to enclosethe connection area between the nail 752 and the handle 754 is generallyrectangular rather than cylindrical. Because of the similarity to device750, further description will be omitted in the interest of brevity.

Reference is now made to FIGS. 25A and 25B, which are partial cut-awayviews illustrating a portion of the radiolucent connector 790, connectedto a drill power unit 792 (only partially shown). In use, the oppositeend of connector 790 is attached to a drill bit (not shown in thefigure), optionally at an angle of 90 degrees. Connector 790 includes aflexible cable 794, configured to transmit the torque and speed from thepower unit 792 to the drill bit. The cable 794 is connected to a coupler796, which is attached to a spring 798. This, in turn, is attached atits other end to additional coupler 800, which is configured forconnection to power unit 792.

In FIG. 25A, a non-activated configuration of apparatus 790 isillustrated. In this configuration, the two couplers 796 and 800 at theends of spring 798 do not engage with each other, and thus even if thepower unit 792 is operated, the torque is not transferred and the drillbit shall not rotate.

FIG. 25B illustrates the “activated” configuration of the drillingassembly. Upon holding component 790, the surgeon must push power unit792 to engage coupler 800, so that the later advances, presses againstspring 798, and engages with the second coupler 796. This clutchmechanism helps prevent accidental operation of the drill.

In an exemplary embodiment of the invention, the actual drilling tool ismade of material that provides for both suitable biocompatibility andbiomechanical properties (e.g., hardness). In an exemplary embodiment ofthe invention, the drilling tool is a standard drill bit used forintra-operatively drilling of holes in the bone. Optionally, the drillbit is made of stainless steel. Optionally, the drill bit is made ofhigh-speed steel or other materials, such as cobalt steel alloys, whichhold their hardness at higher temperatures and thus may be used to drillhard materials.

Other hard materials for constructing the drill tool may be tungstencarbide and other carbides, and polycrystalline diamond (PCD).Optionally, the drilling tool may be coated with material that providesfor additional characteristics, such as heat resistance and/or corrosionresistance and/or hardness. Coating materials that may be used are, forexample, black oxide, titanium nitride (TiN), titanium aluminum nitride(TiAlN), titanium carbon nitride (TiCN), diamond powder and zirconiumnitride. In another exemplary embodiment of the invention, instead of adrill bit a whole saw or other cutting implement may be used. In anexemplary embodiment of the invention, the drill bit is allowed to bemade of less hard materials as it is used only a small number of timesand/or is used for drilling a composite material.

FIGS. 26A-26B illustrate embodiments of the invention in which provisionis made for removal of drilling debris. A device 806 according to suchembodiments includes a suction tube 808 the interior 820 of which isconfigured to be attached to a vacuum source (not shown) and adrill-receiving portion 810 have a hole 812 through which a drill bit814 projects to the drilling site.

Additionally and/or alternatively, drill 814 may be cannulated at 816.Optionally, a suction tube (not shown) is located within cannulation816. Alternatively, there is no suction tube, and the suction isperformed directly from the cannulation or using a separate suctiontube. Optionally, suction of drilling products may be performedsimultaneously from the drill bit cannulation (with or without aseparate suction tube) and from a suction tube 808 as illustrated. Thesuction tube may be made of various materials, such as, but not limitedto, metals and polymers. In some embodiments, the suction tube is madeof a rigid material. In some embodiments, the suction tube is flexible.

In an exemplary embodiment of the invention, the drill is powered bysuction and/or air-flow provided in a surgery, e.g., from a wall mountedcentralized source, and such suction is also used for suction of debrisin addition to or instead of powering the drill.

In some embodiments, the suction process is accompanied by irrigation,for example by sterile saline solution. In such embodiments, duringdrilling, saline is delivered through drill bit cannulation 816, whilesuction of the drilling material is achieved using tube 808.Alternatively, irrigation fluid is introduced through tube 808 and thedrilling products are sucked from an inner tube inside the drill bitcannulation. Optionally, drill bit is not cannulated, and both tubes(for liquid flushing and for suction) are positioned outside the drillbit, one over the other.

Irrigation as described enables cooling of the implant and surroundingtissue while drilling is being performed, to avoid damage of tissueand/or devices, as well as debris removal.

FIG. 26A illustrates another debris removal and irrigation device 822according to some embodiments. Here, device 822 includes a drill 824,which may be cannulated at 826 for irrigation and a separate tube 828for suction which may be placed in proximity to each other duringdrilling by the surgeon. Alternatively, the functions of tube 826 andcannulation 826 may be reversed, or both cannulation 826 and tube 828may be used for suction.

Experiments have been conducted to assess the effectiveness of drillinga bone implant together with evacuation of the drilling material. Duringthe test, a composite material bone plate, made of carbonfibers-reinforced PEEK, was drilled using a drill bit, which wascontained within a polymeric tube. The later was attached to the platewhile its other end was connected to a vacuum pump to allow suction ofthe drilling products. Upon drilling, the drilling products were suckedinto the tube and removed from the plate and its surrounding. Followingdrilling, the plate and the area outside the tube were inspected. Thetest results indicated that only an insignificant amount of residues wasdetected.

In some embodiments of the invention, the drill bit is used to create aperpendicular round hole. Additionally and/or alternatively, the drillbit creates an oblique hole.

Materials and/or coating for the drilling tool may be one or more ofthose described above.

In another exemplary embodiment of the invention, the drill bit is ahole saw.

The drill bit may be of conventional form, or optionally may alsocomprise a tap (thread cutting), to create a thread, at least at part ofthe plate screw hole, so that the screws may be locked to the plate.Alternatively, a separate tap may be used. Additionally and/oralternatively, while screwing the screw into the bone through the plateor nail hole, the screw itself serves as a tap of the plate, and itsthreaded part is locked to the plate or nail.

Exemplary Component Fabrication Methods:

In an exemplary method of fabrication, the core and the sleeve areconstructed from pre-impregnated (prepreg) tapes of carbonfiber-reinforced polymer, preferably thermoplastic polymer such as PEEK.In some embodiments of the invention, the core is formed by compressionmolding. Before molding, the prepreg tapes are pre cut to the size andshape of the mold cavity, and inserted into the mold in accurate totalweight.

Where the bone-supporting components are supplied pre-drilled, thepassages are optionally created during the compression molding process(and not by drilling) Alternatively, passages are created during thecompression molding process and drilling is used following molding toachieve the final desired shape and dimensions of the passages).

The sleeve is then build over the core by spirally winding tape of theprepreg composite, optionally at a pitch of 45 degrees relative to thelongitudinal axis of the core. When more than one tape is used to buildup the sleeve, the adjacent tapes are alternatingly spirally woundclockwise and counterclockwise optionally having a pitch of +/−45 degrelative to the longitudinal axis of the core.

The winding tool for the sleeve optionally includes a heater to heat thetape before the winding, preferably also pre-heating the core, and apressing wheel to create consolidation of the winding tape into thecore. In some embodiments, to strengthen the implant, the process ofcompression molding is performed under high pressure. For example, thepressure may be higher than 100 Atm., optionally higher than 400 Atm.,optionally higher than 700 Atm., optionally higher than 1,000 Atm.

According to some embodiments of the invention, the prepreg tapes areheated during winding. The heating is optionally provided by a laser.Alternatively and/or additionally, an Infra Red source is used forheating the tape during winding. Alternatively and/or additionally, thetape is heated using hot gas such as air.

In some embodiments, a composite material bone implant, for example anintramedullary nail, is produced from a core of longitudinal tapes offiber-reinforced polymer, formed by compression molding, followed bywinding of tapes of fiber-reinforced polymer over the core, togetherwith laser heating. Use of this technique for the manufacturing of abone implant component may eliminate the need of a final compressionmolding (i.e., for the core with the helically wound tapes).

According to some embodiments of the invention, the process ofmanufacturing a composite material bone implant also comprises the stepof slightly expanding the winding, for example, using heat and internalpressure. In an exemplary embodiment of the invention, an intramedullarynail is produced in compression molding followed by tape winding, andthen a rod is axially pushed into the heated mold, to slightly pushoutwardly the core and the winding.

According to some embodiments of the invention, production of acomposite material bone implant involves separate compression moldingfor two or more portions of the implant, where portions are laterconnected, to form the core of the implant. Intramedullary nails ofteninclude a cannulation of about 2-3.5 mm diameter along theirlongitudinal axis, to enable introduction of the nail into the bone overa guide wire. In addition, many of the nails include a few degrees bentor a radius, to comply with the anatomy of the bone.

Production of a bent and cannulated nail in standard compression moldingis possible but generally considered technically difficult. In anexemplary embodiment of the invention, in order to achieve properproduction of such a nail, two moulds are used, each for a half of thenail that comprises “half cannulation”. Following the production of thetwo halves, they can be molded together with mandrel inside, to gethollow core, or alternatively winding is performed around the attachedtwo halves (e.g., tapes are helically wound at ±45 degrees), and theentire construct is then compressed, with a wire in the mold designed tokeep the cannulation along the nail axis.

Optionally, to shorten the time required for the winding process and toreduce costs, winding over the longitudinal core is performed so thatone or more tape is placed over another tape, and each tape is tensionedseparately during winding.

For screws such as 250 in FIG. 10A that include an outer layer 252 of ahard material, this may be applied as a coating or by winding metal tapeover the screw, optionally by using bending wheels. Alternatively thetape may be wound over a screw mandrel, unscrewed from the mandrel, andthen screwed over the composite screw.

Exemplary Methods of Use:

FIG. 28 shows in flow-chart form, an example of how methods according tosome embodiments of the invention may be performed.

At 900, after appropriate preparation, a radiolucent (X-ray transparent)bone-supporting component, for example, a bone plate as described above,formed of a fiber-reinforced polymer matrix composite is positioned inproximity to the fracture site so it overlies the fractured area. At902, the bone plate (optionally, the head) is optionally anchored usingat least one fixation component, for example, a bone screw or peg.Optionally, the targeting guide described herein is used for this.

At 904, taking advantage of the radiolucency of the bone plate, thesurgeon optionally reduces the fracture by positioning the bonefragments optimally for good healing.

At 906, for example, in embodiments in which a drill sleeve is not used,the surgeon optionally drills through the pre-drilled holes or built-indrilling guides in the bone plate to accommodate a desired number ofbone pegs or screws.

The method then proceeds to 914 where the pegs or screws are installed,for example, using a screw guide as in FIG. 21, to provide finalfixation.

In embodiments in which a drill guide and/or other accessories forexample as described in connection with FIGS. 18-21 are optionally used,the method proceeds from 904 to 908, where the radiolucent drill guideand accessories are positioned and optionally attached to the boneplate. At 910, the drill is oriented and positioned by the surgeon asrequired, for example, by inspecting the fractured area visually orunder X-ray through the bone plate and the drill guide. This is againmade possible by the radiolucency of the bone plate and the drillingaccessories formed, and helps assure that the fixation components areoptimally oriented for best support.

At 912, with the drill guide and accessories properly oriented, holesare drilled in the bone. At 914, the fixation components are installed,optionally using the screw guide.

In embodiments in which the bores in the bone plate are blind, both thebone supporting component and the bone may be drilled at 912.Optionally, during the drilling, debris disposal is provided.

Finally, optionally, at 916, the drill guide and other accessories arediscarded after a single use.

Exemplary Dental Implants;

Some embodiments of the invention pertain to dental implants formed of acomposite material, according to embodiments already described for otherbone implants. Optionally, the dental implant is composed of a singlecomponent forming a crown or cap, a screw that goes into the bone, andan abutment intermediate the crown and the screw. Optionally, itcomprises more than one component. Optionally, the abutment and the bonescrew are one composite material component. Optionally, the differentcomponents are made of more than one material, including of anon-composite material.

In some embodiments, the implant is configured so that its strength andelasticity are compatible with the loads exerting on the tooth and/orbone. In an embodiment, the composite material dental implant is coated,for example with material that improves the ability of the implant tointegrate in the bone and enhances bone ingrowth. Such coating may be,for example, porous titanium or hydroxyapatite (HA). In an embodiment,the coating is added using a vacuum plasma spray (VPS) technique. In anexemplary embodiment of the invention, the thickness of the coating isin the range of 50-70 μm.

In some embodiments, a coating is added following implant surfacetreating, for instance grid blast or bombardment of argon ionized ions.Optionally, particles of the coating material (e.g., titanium) areinserted into the implant surface prior to performing the coatingitself, in order to improve the adhesion of the coating to implantsurface. In an embodiment, the composite material bone implant is heatedand the particles are forced/introduced so that they penetrate into theimplant outer layer. In an embodiment, particles of coating material arenot limited to the outer layer of the implant, but rather areincorporated into the entire implant, optionally during the productionof the implant construct.

In some embodiments, the area of the dental implant that contacts softtissue comprises smooth surface, in order to prevent infection at theregion of the implant. Optionally, the smooth surface does not comprisethe coating. Alternatively, the smooth surface comprises smooth,non-porous, coating.

It is expected that during the life of a patent maturing from thisapplication many relevant ultrasound transducers will be developed andthe scope of the term transducer is intended to include all such newtechnologies a priori.

As used herein the term “about” refers to ±10%

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

What is claimed is:
 1. A bone implant comprising: a bone-supportingcomponent comprising a fiber-reinforced polymer matrix composite; afixation component configured to be received in a passage in thebone-supporting component; and a sleeve between the fixation componentand the passage; wherein the sleeve and fixation component areconfigured to slide in relation to one another while the fixationcomponent is received in the passage and the bone implant is fullyimplanted.
 2. The bone implant of claim 1, comprising a locking elementwhich limits sliding of the sleeve and fixation component in relation toone another to a pre-defined travel.
 3. The bone implant of claim 2,wherein the locking element engages with a slot in the fixationcomponent to limit the sliding of the sleeve.
 4. The bone implant ofclaim 3, wherein said locking element passes through a window in thesleeve to engage the slot in the fixation component.
 5. The bone implantof claim 1, wherein the sliding in relation to one another is along alongitudinal extent of the passage.
 6. The bone implant of claim 1,wherein the bone-supporting component comprises an intramedullary bonenail.
 7. The bone implant of claim 6, wherein the sleeve extends throughthe intramedullary bone nail at a non-perpendicular angle to alongitudinal axis of the intramedullary bone nail defined at theposition of the passage.
 8. The bone implant of claim 1, wherein thesleeve is configured to reduce friction-induced wear between thefixation component and the passage.
 9. A bone implant according to claim1, wherein the sleeve is threaded on an outer surface of the sleeve. 10.The bone implant of claim 1, wherein the sleeve comprises metal.
 11. Thebone implant of claim 10, wherein the metal is titanium.
 12. The boneimplant of claim 1, wherein the sleeve is longer than the passage. 13.The bone implant of claim 12, wherein the sleeve protrudes from bothends of the passage.
 14. The bone implant of claim 1, wherein thefixation component comprises a slot configured to be positioned at leastpartially within the sleeve, and a distance of sliding travel of thesleeve and fixation component in relation to one another is pre-definedby a longitudinal length of the slot.
 15. The bone implant of claim 1,wherein the bone-supporting component comprises a body with a headportion at an end of the body, and the passage is in the head portion.16. The bone implant of claim 1, wherein the fixation componentcomprises a bone screw.
 17. The bone implant of claim 16, wherein thebone screw comprises a threaded shaft portion for screwing into bone,and an unthreaded shaft portion received within the passage.
 18. Thebone implant of claim 16, wherein the bone screw is cannulated.
 19. Thebone implant of claim 16, wherein the bone screw comprises a connectorconfigured to engage with a screw insertion tool.
 20. The bone implantof claim 1, wherein the fixation device comprises a fiber-reinforcedpolymer matrix composite.